Best left to our imagination, unless he plans on writing side novels after getting done with A Song of Ice and Fire. There's already disappointment that we probably won't see much of Sothyros and our time in Essos is probably drawing to a close--I see Dany going to Asshai and that's it.

I'm thankful for that.

Spoiler!!! Click to Read!:

Can't believe Danny has been stumbling around that place for 5 books.

__________________"When the snows fall, when the white winds blow, the lone wolf dies, but the pack survives."